1. Field of the Invention
The present invention relates to vehicles such as a unicycle and coaxial two-wheeled vehicle, a control device for such vehicles, and a control method for such vehicles.
2. Description of the Background Art
Conventionally, unstable vehicles such as unicycles, coaxial two-wheeled vehicles and the like which are capable of automatically keeping their balance are known (refer to JP 9-175462 A, JP 3070015 B or WO 00/75001, for example.) Such an unstable vehicle is configured so as to freely swing with the wheel as a supporting point.
JP 9-175462 A discloses a unicycle that provides reduced swinging while being capable of adjusting the self-stabilizing force. This unicycle uses a control moment gyro (CMG) swinging reducing device to reduce the angular velocity of the axle about which the unicycle swings. This improves stability in the front or rearward direction and in the rightward or leftward direction during travel.
JP 3070015 B discloses a control device for controlling running of an unstable vehicle such as a unicycle. The aforementioned control device provides travel of an unstable vehicle by driving a rotor based on the direction, angle, and velocity of inclining of the frame.
WO 00/75001 discloses a personal transporting vehicle that includes a coaxial two-wheeled vehicle. With the aforementioned personal transporting vehicle, the moving direction and velocity of the vehicle is decided based on inclining of the vehicle in the front or rearward direction.
The unicycle according to the aforementioned JP 9-175462 A and the control device according to the JP 3070015 B are not capable of determining whether a user is present or absent on a vehicle. The position of the vehicle body is thus controlled, even when the user ascends or descends onto or from the vehicle, by the swinging reducing device or the control device. For this reason, a self-propelled vehicle such as the vehicle described in JP 3070015 B, in particular, may operate against the user's will when he or she is dismounting the vehicle. This makes dismounting the vehicle difficult.
The personal transporting vehicle disclosed in the aforementioned WO 00/75001 determines the presence or absence of a user on the vehicle via a proximity sensor. Providing the proximity sensor, however, results in increased manufacturing cost.